The GKN Hybrid Power Gyrodrive, an electric flywheel that captures energy as the vehicle brakes, then uses it to drive an electric motor that boosts power and cuts fuel consumption, was developed by Williams Hybrid Power, a division of the company that owns the Williams Formula 1 team. Williams first used it on its F1 cars and supplied it to other manufacturers.

During testing, Gyrodrive-equipped buses saw a whopping 20% bump in fuel efficiency, more than enough to convince GKR and UK public transport operator Go-Ahead to install the system on 500 buses over the next two years, starting in London and Oxford, according to the report.